Ocular (OA) and oculocutaneous (OCA) pigment defects in man and animal homologues are investigated for their clinical, ophthalmologic, biochemical, ultrastructural, genetic, epidemiologic, and pleiotropic features to determine the biochemical or morphologic basis of these defects, with the final objective of improving diagnostic, therapeutic, and counseling means of preventing, ameliorating, or treating these disorders. Investigation of the role of melanosome morphology in skin and hair of the various types of OCA and OA and factors controlling melanosomal development and fate and the search for the ultraviolet light induced keratinocyte-melanocyte messenger are studied not only to improve diagnostic criteria for the various types of albinism, but also to understand the cellular control mechanisms in pigmentogenesis and their pleiotropic effects on vision, neuronal routing, and otic abnormalities. Evidence that the tyrosinase locus regulates the amount and not the structure of the enzyme is pursued. Defects in blood cells, platelets and leucocytes associated with pigment defects are studied for the morphologic, functional and chemical defects. The basic defect in tyrosinase positive albinism is studied for methods of circumventing this block therapeutically. Evidence that normal neuronal routing to the brain is pigment dependent is strengthened by evidence that not only optic but also otic neurons are misrouted in albinos. The function of pigment in the inner ear is studied. Preliminary studies of means of preventing squamous cell carcinoma in albinos in Africa with retinoids is initiated.